Python Web服务器Tornado使用小结

        # check username and password
        if success:
            self.redirect(self.get_argument('next', '/'))
此外，我很多地方都使用了 AJAX 技术，而前端懒得去处理 403 错误，所以我只能改造一下 authenticated() 了：
def authenticated(method):
    """Decorate methods with this to require that the user be logged in."""
    @functools.wraps(method)
    def wrapper(self, *args, **kwargs):
        if not self.current_user:
            if self.request.headers.get('X-Requested-With') == 'XMLHttpRequest': # jQuery 等库会附带这个头
                self.set_header('Content-Type', 'application/json; charset=UTF-8')
                self.write(json.dumps({'success': False, 'msg': u'您的会话已过期，请重新登录！'}))
                return
            if self.request.method in ("GET", "HEAD"):
                url = self.get_login_url()
                if "?" not in url:
                    if urlparse.urlsplit(url).scheme:
                        # if login url is absolute, make next absolute too
                        next_url = self.request.full_url()
                    else:
                        next_url = self.request.uri
                    url += "?" + urllib.urlencode(dict(next=next_url))
                self.redirect(url)
                return
            raise tornado.web.HTTPError(403)
        return method(self, *args, **kwargs)
    return wrapper